Abstract

Simple production techniques are becoming the main issue for low cost mass production of integrated optical devices that have to compete, by terms of end user access network bandwidth, with bulk technologies. Here polymers can play an important role. For the case of ring-like waveguides, the material's low refractive index limits the miniaturization of the radii due to a reduced confinement of the electro-magnetic mode fields as compared to semiconductors [1], that however require an expensive and rather slow e-beam based patterning technique. On the contrary, polymers generally do not require any complicated technological features for waveguide structuring, having the advantage to potentially reach any specification just by designing the appropriate functionality. Despite that, most publications in the domain of micro-resonators point out a presumed difficulty in patterning laterally coupled waveguides with optical fabrication technologies owing to a restriction in establishing the sub-micrometer gap of the asymmetric directional coupler. We propose a simple and fast two-step patterning technique that allows controlling the gap between rings and port waveguides in lateral couplers, as well as independently adjusting the height of the different waveguides. Despite the proximity mode exposure, inducing a strong diffraction of the UV light at the apertures on the mask, the patterning technique resulted very precise, with 0.30^m wide gaps between the ports and the ring.

© 2007 IEEE